Science Systems and Applications, Inc. - Science and Technology with Passion

Solar irradiance

We live under the influence of a relatively quiet star. Despite seemingly prominent cyclic changes in activity, the Sun’s total solar energy output changes by a mere 0.1% during long-term cycles. However, even such minute changes may profoundly affect chemistry and heating of the upper atmosphere and, more importantly, Earth’s climate.

Recent observations collected by specialized Sun-observing instruments onboard the SORCE satellite have created some controversy, with reported long-term changes in the solar spectrum differing in magnitude and spectral dependence fromĀ  previous observations, as well as model predictions. To resolve this controversy, SSAI researchers use additional data supplied by two instruments, primarily the Ozone Monitoring Instrument (OMI) on the Aura satellite, along with the Global Ozone Monitoring Experiment-2 (GOME-2) on the MetOp-B satellite. We also complement contemporary data with historical records compiled from various space-borne experiments. Our results provide a consistent picture of solar variability over a broad wavelength range, and lend strong support to previously developed concepts and models of solar variability. This work represents an important piece of the complex effort to understand climate change.

image2An example of long-term changes in the solar spectrum registered by OMI during the ongoing Solar Cycle 24;
the dotted line shows a representative solar spectrum to illustrate specific features. Credit: NASA GSFC